Update README.md

README.md

@@ -112,7 +112,7 @@ Please cite the [Calcformers paper](https://arxiv.org/abs/2305.15017) as follows
     title = "Calc-X and Calcformers: Empowering Arithmetical Chain-of-Thought through Interaction with Symbolic Systems",
     author = "Marek Kadlčík and Michal Štefánik and Ondřej Sotolář and Vlastimil Martinek",
     booktitle = "Proceedings of the The 2023 Conference on Empirical Methods in Natural Language Processing: Main track",
-    month = december,
+    month = dec,
     year = "2023",
     address = "Singapore, Singapore",
     publisher = "Association for Computational Linguistics",